1. Field of the Invention
The present invention relates to toggle clamps, and more particularly, to a toggle clamp having a latch mechanism for securing the clamp in a clamped or closed position. Additionally, the latch mechanism may also be used to secure the clamp in an unclamped or open position.
2. Description of the Related Art
Toggle clamps, including a clamping arm which pivots between a released and a clamped position, are used extensively to hold a workpiece in place for further processing. Toggle clamps are quickly engagable and disengagable with the workpiece while providing considerable holding capacity and exerting a substantial clamping force to hold the workpiece.
Toggle clamps can be held in the clamped position through a variety of means, including maintaining the force applied to the handle or the actuating arm of the clamp. Clamp mechanisms of this type utilize a power cylinder, either pneumatic or hydraulic. Various types of a releasable latch assembly have also been used to hold a toggle clamp in both a clamped, locked position or an unclamped, released position. Finally, some clamps develop locking pressure by passing the links of the toggle clamp through an over center position. Passing through an over center position subjects the links and pivot pins to very high loads, resulting in increased wear and potential deformation of the clamp components, thereby reducing the life of the clamp. Further, vibration conditions may cause release of the clamp. Therefore, a positive latch mechanism for preventing unintentional unclamping is desirable to securely retain the toggle clamp in a clamped position.
One approach to a toggle clamp having a locking mechanism is disclosed in U.S. Pat. No. 5,165,148 wherein a latch lever is mounted on a cross pin of the clamp handle. A knob on the release lever projects into a recess on the base of the clamp to lock the clamp in a clamped position. Such a locking mechanism is suitable for straight line action toggle clamps.
While such an approach is useful, it is desired to have a toggle clamp rotatable about a base including a releasable latch mechanism to secure the clamp in the closed position and to prevent the clamp from releasing during use. Additionally, it is desirable to have a toggle clamp which can be latched in an open, unclamped position. Such a latch mechanism prevents a clamp from inadvertently closing, thus causing damage to the workpiece or associated machinery.